In the past, various methods have been used to control either the attitude or orbital velocity of a spacecraft or space vehicle. For example, it is well known to use launch vehicles, such as a space shuttle, with gimbaled thrusters for velocity control. In addition, chemical thrusters have been body-fixed to the spacecraft in order to perform a number of functions. One function performed is to precess attitude by timing chemical thruster pulses relative to an inertial reference, such as the sun or earth. Such body-fixed chemical thrusters have been used to control the spin rate and attitude of a spacecraft during thrusting for orbit raising.
While many of the known methods for controlling attitude or orbital velocity have performed adequately, there is room for improvement. In particular, prior methods of control require separate thrusters to perform attitude control and orbital velocity control. In addition, prior methods of control require expensive chemical propulsion systems to perform attitude and orbital velocity control.